https://techcrunch.com/2019/03/30/cmu-team-develops-a-robot-and-drone-system-for-mine-rescues/

On our final day in Pittsburgh, we find ourself in a decommissioned coal mine. Just northeast of the city proper, Tour-Ed’s owners run field trips and tours during the warmer months, despite the fact that the mine’s innards run a constant 50 degrees or so, year round.

With snow still melted just beyond the entrance, a team of students from Carnegie Mellon and Oregon State University are getting a pair of robots ready for an upcoming competition. The small team is one of a dozen or so currently competing in DARPA’s Subterranean Challenge.